"Now pretend you don’t know a single person who wears Google Glass… and take a walk outside. Anywhere you go in public – any store, any sidewalk, any bus or subway – you’re liable to be recorded: audio and video. Fifty people on the bus might be Glassless, but if a single person wearing Glass gets on, you – and all 49 other passengers – could be recorded. Not just for a temporary throwaway video buffer, like a security camera, but recorded, stored permanently, and shared to the world."
(hat-tip to Andrew Sullivan)